Among prominent philosophers, there are two distinct viewpoints on time. Isaac Newton and some other philosophers assert that time is a fundamental part of the structure of the Universe and a dimension or plane in which events occur in relative sequence.

The opposing view as propounded by Gottfried Leibniz and Immanuel Kant is that time is neither an event nor a thing, and can neither be measured nor can it be travelled. They regard time to be an intellectual structure (together with space and number) created by humans for the convenience of defining the sequence of events.

St. Augustine of Hippo called time a “distention” of the mind (Confessions 11.26) in which the past is based on memory, the present based on attention, and the future based on expectation. A similar view was expressed by Henri Bergson who said that time was neither a thing, nor a mental construct, but was Duration, that comprised creativity and memory that lead to reality.